JPH11287524A - Natural circulation combination type air-conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effect high-efficient operation without consuming a wasteful power by providing a refrigeration cycle switch means to switch forced circulation operation and natural circulation operation according to an indoor heat load. SOLUTION: A compressor 3, a condenser, an expansion valve 5, and an evaporator are interconnected, in the order, through respective pipings to form a refrigeration cycle, and forced circulation operation by the compressor 3 and natural circulation operation by a natural circulation refrigeration cycle system are switched. A so formed air conditioner comprises an indoor thermal load detecting means 100b; a natural circulation refrigeration cycle capacity calculating means 100C; and a refrigeration cycle switch means 100d to switch forced circulation operation and natural circulation operation according to the cooling capacity of the natural circulation operation and an indoor heat load.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner in which, when the outside air temperature is low, the operation of a compressor is stopped to perform air conditioning by natural circulation of a refrigerant, and when the outside air temperature is high, air conditioning is always performed by an operation of the compressor. The present invention relates to an air conditioner combined with natural circulation.

[0002]

2. Description of the Related Art FIG.
FIG. 8 is a configuration diagram of a refrigeration cycle of a conventional air conditioner combined with natural refrigerant circulation disclosed in Japanese Patent Publication No. 8; In the figure, 101
Is a compressor that compresses the refrigerant gas, 102 is a condenser that exchanges heat between the refrigerant and the outside air to condense the refrigerant gas, 109 is a liquid receiver that stores the condensed refrigerant, 103 is a decompression device that decompresses the condensed refrigerant, 104a is an evaporator for evaporating the condensed refrigerant by exchanging heat with the condensed refrigerant and room air, 105 is a condenser fan of the condenser 102, 106 is an evaporator fan of the evaporator 104, 113 is a refrigerant liquid and a refrigerant gas. The refrigeration cycle of the forced circulation is constituted by sequentially connecting these devices by piping. Reference numeral 110 denotes a decompression device 103 of the liquid receiver 109.
It is a pipe trap provided on the side.

Further, a solenoid valve 111, a natural circulation evaporator 104b, and a check valve 112 are provided in a bypass pipe 131 connecting the outlet side of the pressure reducing device 103 of the forced circulation refrigeration cycle and the discharge side of the compressor 101. Are sequentially provided, and the condenser, the condenser 102, and the decompression device 103 are sequentially connected by a pipe 122, thereby forming a natural circulation refrigeration cycle. The solenoid valve 111 allows the refrigerant from the condenser 102 to flow to the natural circulation evaporator 104b, and the check valve 112 allows the refrigerant during the natural circulation cooling operation to flow to the condenser 102, forcing forced circulation cooling. This prevents the refrigerant discharged from the compressor 101 during operation from flowing to the natural circulation evaporator 104b. Also,
In the natural circulation cooling, the condenser is installed higher than the evaporator in order to circulate the refrigerant as the heat medium by its own weight difference.

Next, this operation will be described. First,
When the power is turned on, when the outside air temperature is high, the control unit closes the solenoid valve 111 of the natural circulation refrigerant circuit to open the compressor 1.
01 is operated to operate the compressor 10
1, condenser 102, liquid receiver 109, pipe trap 11
0, since it sequentially flows through the decompression device 103, the forced circulation evaporator 104a, and the accumulator 113, the forced circulation evaporator 104a cools and cools the indoor air.

On the other hand, when the outside air temperature is low, the compressor 10
1 is stopped and the solenoid valve 111 of the natural circulation refrigerant circuit is controlled so as to be opened.
9. If the resistance is lower than the pressure reducing device 103, the solenoid valve 111,
Since the natural circulation evaporator 104a and the check valve 112 flow sequentially, the natural circulation evaporator 104a cools and cools the room air.

[0006]

The conventional air conditioner combined with natural circulation is configured as described above, and therefore requires an evaporator for natural circulation and an evaporator for forced circulation.
There is a drawback that the structure is large and expensive due to the complicated structure, for example, a liquid receiver is required at the condenser outlet.

Further, there are various problems caused by switching between the natural circulation refrigerant circuit and the forced circulation refrigerant circuit, for example, the cooling capacity due to the compression of the refrigerant liquid of the compressor and the shortage of the refrigerant during the natural circulation cooling. However, there has been a problem that various troubles occur because sufficient measures and configurations have not been taken with respect to a decrease in the temperature.

[0008] This type of air conditioner combined with natural circulation is used as a cooling device in a station building of a mobile communication base station such as a mobile phone, and is installed on the top of the station building of the mobile communication base station. In many cases, if there is a height restriction when transporting a station building by truck, etc., an outdoor unit must be installed by mounting an outdoor unit installation base on the wall of the station building, etc. There are drawbacks such as the height difference between the unit and the outdoor unit is reduced, and the installation work is difficult.

[0009] The air conditioner combined with natural circulation of the present invention comprises:
It was made to solve the above problems,
In an air conditioner that can switch between forced circulation operation by a compressor and natural circulation operation by a natural circulation refrigeration cycle system, refrigeration that switches between forced circulation operation and natural circulation operation according to the cooling capacity and indoor heat load in natural circulation operation It is an object of the present invention to provide a device provided with cycle switching means.

[0010]

The air conditioner with natural circulation according to the present invention is an air conditioner for cooling a room by sequentially connecting a compressor, an outdoor heat exchanger, an expansion valve and an indoor heat exchanger by piping. A conditioner, the evaporator outlet and the condenser inlet are connected by a bypass pipe via a check valve, and the opening degree of the expansion valve is controlled so that forced circulation operation and natural circulation by the compressor refrigeration cycle system are performed. An air conditioner that can switch between a cooling operation by a refrigeration cycle system and an indoor heat load detection unit, a refrigeration cycle capacity calculation unit that calculates a cooling capacity in the natural circulation operation, and a refrigeration cycle capacity calculation unit. Refrigeration cycle switching means for switching between the forced circulation operation and the natural circulation operation according to the cooling capacity in natural circulation operation and the indoor heat load detected by the indoor heat load detection means. Those were example.

Further, the air conditioner combined with natural circulation according to the present invention comprises an indoor temperature detecting means and an outside air temperature detecting means, and the natural circulation refrigeration cycle capacity is obtained from the indoor temperature and the outside air temperature. .

The air conditioner of the present invention also includes a compressor, an outdoor heat exchanger, an expansion valve, and an indoor heat exchanger which are sequentially connected by piping to cool the room. The evaporator outlet and the condenser inlet are connected by a bypass pipe via a check valve, and the degree of opening of the expansion valve is controlled so that the forced circulation operation by the compressor refrigeration cycle system and the natural circulation refrigeration cycle system An air conditioner that can switch between a cooling operation and an accumulator provided in parallel with the bypass pipe so as to store a difference between a refrigerant amount required in the forced circulation operation and the natural circulation operation, and the forced circulation. A refrigerant recovery means for recovering the refrigerant stored in the accumulator when switching from the operation to the natural circulation operation is provided, and the natural circulation operation is performed after the refrigerant is recovered. .

In the air conditioner with natural circulation according to the present invention, the refrigerant recovery control means includes a high-pressure pipe from the compressor outlet to the expansion valve inlet and a low-pressure pipe from the expansion valve outlet to the compressor inlet. And a high / low pressure bypass valve for controlling the amount of refrigerant flowing through the second bypass pipe, and controlling the opening degree of the expansion valve and the high / low pressure bypass valve. is there.

Further, the air conditioner with natural circulation according to the present invention comprises an indoor heat load detecting means, a refrigeration cycle capacity calculating means for calculating a cooling capacity in each of the refrigeration cycles,
According to the cooling capacity in the natural circulation refrigeration cycle system obtained by the refrigeration cycle capacity calculation means and the indoor heat load detected by the indoor heat load detection means, the forced circulation operation by the compressor refrigeration cycle system and the natural circulation refrigeration cycle The system is provided with refrigeration cycle switching means for switching between natural circulation operation by the system and performing the refrigerant recovery control.

Further, the air conditioner with natural circulation according to the present invention is characterized in that, in each of the refrigeration cycle of the compressor refrigeration cycle system or the natural circulation refrigeration cycle system, the refrigeration cycle system of the compressor or the natural circulation refrigeration cycle system. When an abnormality is detected from one of the refrigeration cycles, the refrigeration cycle is switched to another refrigeration cycle in which no abnormality is detected.

Further, the air conditioner with natural circulation according to the present invention further comprises a heat exchanger temperature detecting means for detecting the temperature of the evaporator or the condenser, wherein the heat exchanger temperature detecting means and the refrigeration cycle are provided. The operation state of each refrigeration cycle of the compressor refrigeration cycle system or the natural circulation refrigeration cycle system is detected by a capacity calculation unit.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a refrigerant circuit diagram showing a natural circulation combined type air conditioner according to Embodiment 1 of the present invention. In the drawing, reference numeral 1 denotes an outdoor unit, 2 denotes an indoor unit, and 3 denotes an indoor unit. A compressor 4 for compressing the refrigerant is provided in the outdoor unit 1, a condenser as an outdoor heat exchanger, 5 is a pressure reducing device such as a capillary tube or an expansion valve, and 6 is provided in the indoor unit 2. An evaporator as an indoor heat exchanger, 7 a fan of the condenser, 8 a fan of the evaporator, and 9 a bypass provided with a check valve 10 for bypassing the compressor 1 during natural circulation operation. Piping. 11 is a liquid pipe, and 12 is a gas pipe.

The air conditioner combined with natural circulation according to the first embodiment is used, for example, in a place where cooling is required throughout the year. When the indoor temperature is lower than the outside air temperature, the forced circulation operation by the compressor 3 is performed. When the temperature is higher than the outside air temperature, the compressor 3 is stopped, and the natural circulation operation using the cold of the outside air is performed.

FIG. 2 is a mobile communication station base of the air conditioner with natural circulation according to the first embodiment. For example, it is an installation configuration diagram installed in a relay station of a mobile phone. 200
Is a building having an object to be cooled therein, such as a relay station of a mobile phone, and 201 is an indoor unit 2 installed inside the building and an outdoor unit 1 installed outside the building, for example, installed above the building. An indoor / outdoor communication line to be connected, 202 is a wired remote controller (hereinafter, referred to as a remote controller) for operating the air conditioner from the outside, and 203 is a remote control communication line for connecting the indoor unit 2 and the remote controller 202.

In the first embodiment, the outdoor unit 1 is connected to the indoor unit 2 by a liquid pipe 11, a gas pipe 12, and an indoor / outdoor communication line 201, and the condenser 4 of the outdoor unit 1 evaporates the indoor unit 2. It is arranged at a position higher than the vessel 6. The indoor unit 2 is connected to a remote controller 202 via a remote controller communication line 203. Remote control 2
The indoor unit 2 which has received the operation command from the remote controller 02 via the remote control communication line 203 transmits the operation command and information such as the indoor temperature to the outdoor unit 1 via the indoor / outdoor communication line 201, and the outdoor unit 1 optimizes the operation. Select a proper refrigeration cycle and perform cooling operation.

First, the forced circulation operation will be described. When the opening degree of the expansion valve 5 is set to an appropriate opening degree to reduce the pressure of the refrigerant liquid that has exited the condenser 4 into two-phase wet steam, and the compressor 3 is operated, the check valve 10 The compressor 3 is closed by the pressure difference between the discharge pressure and the suction pressure of the compressor 3 to form a forced circulation cycle.

Next, the natural circulation operation when the outside air temperature is lower than the room temperature will be described. When the opening of the expansion valve 5 is fully opened to reduce the pressure loss in the refrigerant circuit, the check valve 10 is opened by the flow of the refrigerant, and a natural circulation cycle is formed. Here, the refrigerant tends to flow also in the flow path passing through the compressor 3, but since the flow resistance inside the compressor 3 is much larger than the flow resistance of the bypass pipe 9, the flow rate of the refrigerant passing through the compressor 3 is It becomes negligibly small with respect to the flow rate of the refrigerant passing through the bypass pipe 9.

As described above, the air conditioner combined with natural circulation is provided with the forced circulation operation and the natural circulation operation, and is configured to switch in accordance with the outside air temperature and the room temperature. Since only the input of the fan 7 of the evaporator 6 and the fan 8 of the evaporator 6 are required, the annual power consumption can be greatly reduced.

Next, a method of controlling switching between forced circulation operation and natural circulation operation of the air conditioner with combined use of natural circulation according to the first embodiment will be described with reference to FIGS. FIG. 3 is a block diagram showing a configuration of a control unit in the air conditioner with natural circulation according to the first embodiment, and FIG. 4 is a flowchart showing a control sequence in a case where a cycle is switched between room temperature and outside air temperature. .

As shown in FIG. 3, reference numeral 100a designates an outdoor unit controller for switching the refrigerating cycle between the forced circulation operation and the natural circulation operation and controlling the compressor 3, the fan 7 of the condenser 4, the expansion valve 5, and the like. For example, a sensor 1 for detecting the outside air temperature, 110b a sensor 2 for detecting the condenser pipe temperature, a sensor 3 for 110c, and the sensors 11 for 100b
An indoor heat load detecting means 100 for detecting an indoor heat load based on single or plural pieces of detection information 0a to 110c and information obtained from the indoor unit 2 via the indoor / outdoor communication line 201;
b is a natural circulation refrigeration cycle capacity calculation means for calculating the capacity of the natural circulation refrigeration cycle based on single or plural detection information of the sensors 110a to 110b and information obtained from the indoor unit 2, and 100d is forced circulation or natural circulation. Refrigeration cycle switching means for switching each refrigeration cycle of 1
00e is a compressor refrigeration cycle controller that controls the compressor refrigeration cycle operation that is a forced circulation operation, 100f is a natural circulation refrigeration cycle controller that controls the natural circulation refrigeration cycle operation that is a natural circulation operation, and 120a is an internal / external communication line 201.
An indoor / outdoor communication control unit A 210 for transmitting / receiving information to / from the indoor unit 2 through the indoor unit 2 is an indoor unit control unit for controlling the indoor unit 2, a sensor a 211 for detecting the pipe temperature, and a 212 for detecting the indoor temperature. The sensors b and 220 are an indoor / outdoor communication control unit B for transmitting / receiving information to / from the outdoor unit 1 via the inside / outside communication line 201.

The indoor unit 2 compares the indoor temperature detected by the sensor a211 and another temperature detected by the sensor b212, for example, the pipe temperature, with the indoor / outdoor communication control unit (B) 220 via the inside / outside communication line 201. To the outdoor unit 1. The outdoor unit 1 determines the outdoor unit control unit 100 from the information such as the indoor temperature received by the indoor / outdoor communication control unit (A) 120a and the outside air temperature detected by the sensor 1 110a.
The indoor heat load and the cooling capacity in the natural circulation refrigeration cycle are calculated by the indoor heat load detection means 100b and the refrigeration cycle capacity calculation means 100c.

In the natural circulation operation, when the outside air temperature is lower than the room temperature, the cooling capacity changes according to the temperature difference, and the cooling capacity is simply calculated based on the outside air temperature and the room temperature. It is possible. In response to a command from the indoor heat load detecting means 100b and the refrigeration cycle capacity calculating means 100c, the refrigeration cycle switching means 100d, for example, when the indoor heat load is high and the cooling capacity in the natural circulation refrigeration cycle is small, the compressor refrigeration cycle. Control unit 10
The forced circulation operation is performed by driving the compressor 3, the fan 7 of the condenser 4, and the expansion valve 5 by 0e.

When the cooling capacity of the natural circulation refrigeration cycle is large, the natural circulation refrigeration cycle control unit 100
At f, the compressor 3 is stopped, and the fan 7 and the expansion valve 5 of the condenser 4 are driven to perform natural circulation operation. Here, even if the indoor heat load is low, if the cooling capacity in the natural circulation refrigeration cycle is small, for example, 0, the natural circulation refrigeration cycle control unit 100f stops the fan 7 of the condenser 4 and increases the power consumption. Operate with restraint.

Next, a control flowchart of the first embodiment shown in FIG. 4 will be described. When the operation is started in step S401, the indoor heat load is calculated in step S402, for example, at the indoor temperature. If the room temperature is equal to or higher than the predetermined temperature t1, a forced circulation operation is performed in step S403. If it is determined in step S402 that the room temperature is lower than the temperature t1, it is determined in step S404 whether the room temperature is lower than the predetermined temperature t2. When the room temperature is equal to or higher than the temperature t2, the previous refrigeration cycle is determined in step S405, and in the case of the previous forced circulation operation, the forced circulation operation is performed in step S403. If the previous refrigeration cycle is not the forced circulation operation, the cooling capacity in the natural circulation refrigeration cycle is determined in step S407 based on whether a value obtained by subtracting the outside air temperature from the room temperature is higher than t4. If the indoor / outdoor temperature difference is higher than t4, it is determined that there is a cooling capacity, and natural circulation operation is performed in step S408.

Next, if the room temperature is lower than the temperature t2 in step S404, it is determined in step S406 whether the room temperature is higher than t3. Room temperature is t3
In the above case, the cooling capacity in the natural circulation refrigeration cycle is determined in step S407 based on whether a value obtained by subtracting the outside air temperature from the room temperature is higher than t4. If the indoor / outdoor temperature difference is equal to or greater than t4, it is determined that there is a cooling capacity, and natural circulation operation is performed in step S408. Indoor and outdoor temperature difference is t
If the temperature is lower than 4 or if it is determined in step S406 that the room temperature is lower than t3, the cooling operation is turned off by stopping the fan 7 of the condenser 4 in step S409.
F.

In the first embodiment, an example in which a refrigeration cycle is selected in the outdoor unit 1 has been described. However, when a refrigeration cycle is selected in the indoor unit 2 or the remote controller 202,
May be commanded.

In addition to the operation setting by the wired remote controller 202 as in the first embodiment, the remote controller communication line 2
It is also possible to use a wireless remote controller or an operation switch provided on the main body without using 01.

Embodiment 2 FIG. In the first embodiment, an example in which the indoor temperature is detected by the indoor unit 2 and transmitted to the outdoor unit 1 by communication has been described. However, air circulation with natural circulation according to the second embodiment of the present invention shown in FIG. The indoor temperature may be directly input by the outdoor unit 1 as shown in the control block diagram of the machine. In this case, the indoor / outdoor communication line 201 as shown in FIG. 2 becomes unnecessary. The fan 8 of the evaporator 6
May be driven by the outdoor unit control unit 100a.

In the second embodiment of the present invention, the indoor heat load is detected at the indoor temperature. However, the indoor heat load may be determined based on, for example, a combination of the indoor temperature and the outdoor temperature, a compressor operating rate, and the like. For example, if the outside air temperature is constant, it can be said that the indoor heat load is small if the time until the room temperature decreases to a constant temperature by the forced circulation operation is short.

In the second embodiment of the present invention, the natural circulation refrigeration cycle capacity is obtained from the difference between the room temperature and the outside air temperature. Alternatively, it may be based on a compressor operation rate or the like.
For example, if the amount of heat generated in the room is constant, the outside air temperature can be said to be low if the time until the room temperature decreases to a constant temperature by the forced circulation operation is short.

Embodiment 3 Hereinafter, for example, a cooling device will be described as an air conditioner with natural circulation according to Embodiment 3 of the present invention. FIG. 6 shows Embodiment 2 of the present invention.
FIG. 1 is a refrigerant circuit diagram showing an air conditioner combined with natural circulation according to the present invention. In the figure, 13 is an on-off valve for preventing the refrigerant from flowing into the accumulator 14 for preventing the liquid from returning to the compressor 3 in the case of a transient phenomenon or overfilling of the refrigerant, and 16 is the outlet of the compressor 3 A high-low pressure bypass valve 18 for connecting a high-pressure pipe at the outlet of the compressor 3 to a low-pressure pipe at the inlet of the accumulator 14; The same reference numerals as those in FIG. 1 denote the same or corresponding parts.

The air conditioner with natural circulation according to the third embodiment of the present invention comprises an outdoor unit 1 and an indoor unit 2 as well as a liquid pipe 11 and a gas pipe 12 for connecting them, as in the first embodiment. It is composed of The outdoor unit 1 includes a compressor 3 for compressing the refrigerant gas, a condenser 4 for cooling and liquefying the refrigerant gas, a fan 7 for forcibly blowing outside air to an outer surface of the condenser 4, Expansion valve 5 which decompresses the high-temperature and high-pressure refrigerant liquid which has exited the compressor 4 and turns it into wet vapor in a two-phase state, to prevent liquid from returning to the compressor 3 in the event of a transient phenomenon or overfilling of refrigerant. An accumulator 14, an on-off valve 13 for bypassing the compressor 3 and the accumulator 14 during natural circulation operation, a bypass pipe 9 via a check valve 10, and a second for preventing refrigerant from flowing into the compressor 3 during natural circulation operation. It comprises a check valve 16 and a second bypass pipe 17 via a high / low pressure bypass valve 18 connecting the high pressure pipe at the outlet of the compressor 3 and the low pressure pipe at the inlet of the accumulator 14. The indoor unit 2 includes an evaporator 6 for evaporating wet steam flowing from the liquid pipe 11 by an air conditioning load, and a fan 8 of the evaporator.

In the third embodiment, in order to maximize the cooling capacity in the natural circulation operation, it is necessary to charge a larger amount of refrigerant than in the forced circulation operation. Therefore, when the refrigerant amount is such that the cooling capacity of the natural circulation operation is maximized, the surplus refrigerant is accumulated in the accumulator 14 during the forced circulation operation as described above, and this surplus refrigerant is discharged during the natural circulation operation during operation switching. It is necessary to perform a refrigerant recovery operation for returning to the refrigerant circuit.

As a refrigerant recovery operation, there is also a method in which the opening of the expansion valve 5 is fully closed to perform a forced circulation operation. However, in this method, the suction pressure of the compressor 3 drops sharply. The refrigerant liquid sucked into the compressor 3 foams, and the refrigerating machine oil flows out into the refrigerant circuit together with the discharged gas, and the amount of the refrigerating machine oil inside the compressor 3 decreases, and there is a danger of burning due to poor lubrication. In particular, in the case of a scroll compressor, the amount of oil supplied to a sliding portion is reduced due to a decrease in suction pressure or a foaming of a refrigerant liquid inside the compressor 3, and the sliding portion is thermally deformed due to a rise in temperature, which may lead to breakage. Problems arise. In addition, the refrigerating machine oil flowing into the refrigerant circuit causes an increase in pressure loss, which causes a phenomenon that the cooling capacity of the operation is reduced.

FIG. 7 is a block diagram showing a configuration of a control unit in an air conditioner combined with natural circulation according to Embodiment 3 of the present invention, and FIG. 8 is a flowchart showing an operation control process. As shown in FIG. 7, the open / close valve 13 and the high / low pressure bypass valve 18 are driven by the outdoor unit control unit 100. FIG. 7 shows an example in which the indoor temperature is detected by the indoor unit 2 and transmitted to the outdoor unit 1 by communication as in FIG. 3, but the outdoor unit 1 may directly input the indoor temperature. Further, the fan 8 of the evaporator 6 may be driven by the outdoor unit controller 100a.

Next, the operation of the air conditioner with combined use of natural circulation according to the third embodiment of the present invention will be described with reference to FIG. First, in step S403, a forced circulation operation is performed.
The on-off valve 13 is open, the high / low pressure bypass valve 18 is closed, and the expansion valve 5
Is a state where the opening degree is set to an appropriate degree for reducing the pressure of the refrigerant liquid that has exited the condenser 4 into two-phase wet steam. If it is determined in step S402 that the room temperature is lower than the temperature t1, it is determined in step S404 whether the room temperature is lower than a predetermined temperature t2. When the room temperature is equal to or higher than the temperature t2, the previous refrigeration cycle is determined in step S405, and in the case of the previous forced circulation operation, the forced circulation operation is performed in step S403.

If the previous refrigeration cycle is not the forced circulation operation, the cooling capacity in the natural circulation refrigeration cycle is determined in step S407 based on whether the value obtained by subtracting the outside air temperature from the room temperature is higher than t4. If the indoor / outdoor temperature difference is equal to or greater than t4, it is determined that there is a cooling capacity, and furthermore, step S50
At 3, it is determined whether the refrigerant recovery has been performed. If the refrigerant has been recovered, a natural circulation operation is performed in step S408.

If it is determined in step S404 that the room temperature is lower than t2, and if it is determined in step S406 that the room temperature is higher than t3, in step S501, for example,
The effect of the natural circulation operation is calculated based on whether the outdoor temperature is lower than t5. If the outdoor temperature is equal to or greater than t5, it is determined that the effect of the natural circulation operation is low or ineffective. This is because when the outside air temperature is high, even if it is determined in step S407 that there is a cooling capacity in the natural circulation refrigeration cycle, the room temperature at that time is high and the cooling capacity is relatively small. This is because the operation ends in a short time and the room temperature becomes equal to or higher than t1. in this case,
In step S409, power consumption is suppressed by stopping the fan 3 of the condenser 4 and the cooling operation is turned off.

If it is determined in step S501 that the outdoor temperature is lower than t5, it is determined that the effect of the natural circulation operation is high, and control is performed by the refrigerant recovery control means in step S502, and step S408 is performed via step S407.
Perform natural circulation operation at. When it is determined in step S406 that the room temperature is lower than t3, and when step S501
If it is determined in step S407 that the outdoor temperature is higher than t5, if it is determined in step S407 that the indoor / outdoor temperature difference is lower than t4, and if it is determined in step S503 that the refrigerant recovery has not been performed, step S409 is performed. The cooling operation is turned off, for example, by stopping the fan 7 of the condenser 4.

The refrigerant recovery control means executed in step S502 opens the high / low pressure bypass valve 18 and changes the opening of the expansion valve 5 to an opening at which the evaporator outlet is overheated. In the refrigerant recovery control operation, the accumulator 14
The refrigerant liquid therein is evaporated by the superheated gas from the evaporator 6 and the superheated gas discharged from the compressor 3 flowing through the second bypass pipe 17 via the high / low pressure bypass valve 18.
Next, the compressor 3 is stopped, the on-off valve 13 is closed to prevent the refrigerant from flowing into the accumulator 14, and the high / low pressure bypass valve 18 is closed, so that the degree of opening of the expansion valve 5 is adjusted in the refrigerant circuit. Fully open to reduce the pressure loss at step S4
07, the flow shifts to the natural circulation operation in step S408 via step S503.

In the third embodiment of the present invention, step S
At 501, the effect of the natural circulation operation is determined based on whether the outdoor unit is smaller than a certain value t5.
The determination may be made based on whether “the temperature t1-the outdoor temperature at which the forced circulation operation is started” is smaller than the fixed value t5.

By switching the operation according to such a procedure, the refrigerant accumulated in the accumulator 14 can be recovered to the natural circulation circuit without lowering the suction pressure of the compressor 3, thereby improving the reliability of the compressor 3. In addition to the effect of being able to perform the operation, when the effect of the natural circulation operation is small or ineffective, there is an effect that there is no need to start up the compressor 3 and consume power. Further, the life of the expansion valve can be extended without frequently controlling the opening degree of the expansion valve 5.

In the third embodiment of the present invention, step S
At 409, an example in which the cooling operation is turned off by stopping the fan 3 of the condenser 4 is shown.
Is stopped, when the fan 8 of the evaporator 6 is operated and the expansion valve 5 is open, the natural circulation operation is continued although the capacity is reduced.

Embodiment 4 FIG. 9 is a control flowchart showing an air conditioner with combined use of natural circulation according to the fourth embodiment of the present invention. When it is not desired to lower the room temperature to a predetermined temperature or lower, as shown in FIG. After stopping the fan and controlling the capacity,
When the room temperature becomes smaller than t6 at 504, the opening of the expansion valve 5 is fully closed at step S505 to stop the flow of the refrigerant. Thus, the cooling operation can be stopped. Also, in step S505, the evaporator 6
The same effect can be obtained even if the fan 8 is stopped.

Embodiment 5 Hereinafter, for example, a cooling device will be described as an air conditioner with combined use of natural circulation according to Embodiment 5 of the present invention. FIG. 10 is a control block diagram showing an air conditioner combined with natural circulation according to Embodiment 5 of the present invention. In the figure, reference numeral 100g denotes an abnormality detecting means for detecting an abnormality in the operation state, and the same reference numerals as those in FIGS. 3, 5, and 7 denote the same or corresponding parts.

FIG. 11 is a control flowchart showing the operation at the time of cycle switching when an abnormality is detected. If an abnormality is detected by the abnormality detecting means 100g shown in FIG. 10 in step S601 during operation (step S401), the cycle is switched to another cycle in steps S602 and S603 according to the current cycle. That is, when the forced circulation operation is being performed, the operation is switched to the natural circulation operation in step S408. When the natural circulation operation is being performed, the operation is switched to the forced circulation operation in step S403.

FIG. 12 is a control block diagram showing a specific example of the abnormality detection of the air conditioner combined with natural circulation according to the fifth embodiment of the present invention. In the figure, 100h is a heat exchanger temperature detecting means. For example, the condenser pipe temperature sensor 11
0b and the heat exchanger temperature detecting means 100h from the detected values of the evaporator pipe temperature sensor 212 received via the indoor / outdoor communication control section (A) 120a and the indoor / outdoor communication control section (B) 220.
When the pipe temperature corresponding to the capacity calculated by the refrigeration cycle capacity calculation means 100c has not been reached, it is determined that the refrigeration cycle being performed is not normal.

FIG. 11 shows an example in which the evaporator pipe temperature is detected by the indoor unit 2 and transmitted to the outdoor unit 1 by communication, as in FIGS. The pipe temperature may be input.

In the fifth embodiment of the present invention, the abnormality is detected based on the pipe temperature. However, the abnormality may be determined based on the refrigerant pressure, the current value, or the like.

[0055]

As described above, the air conditioner combined with natural circulation according to the present invention cools the room by sequentially connecting the compressor, the outdoor heat exchanger, the expansion valve and the indoor heat exchanger by piping. An air conditioner, the evaporator outlet and the condenser inlet are connected by a bypass pipe via a check valve, and the degree of opening of the expansion valve is controlled so that forced circulation operation by the compressor refrigeration cycle system and natural An air conditioner capable of switching between a cooling operation by a circulation refrigeration cycle system and an indoor heat load detection unit, a refrigeration cycle capacity calculation unit for calculating a cooling capacity in the natural circulation operation, and the refrigeration cycle capacity calculation unit. Refrigeration cycle switching means for switching between the forced circulation operation and the natural circulation operation according to the determined cooling capacity in the natural circulation operation and the indoor heat load detected by the indoor heat load detection means. Since the example was configuration, without consuming unnecessary power, there is an effect that it is more high rate of operation.

Further, the air conditioner with natural circulation of the present invention includes an indoor temperature detecting means and an outside air temperature detecting means,
Because the natural circulation refrigeration cycle capacity was determined by the room temperature and the outside air temperature, by a simple method,
There is an effect that the natural circulation refrigeration cycle capacity can be calculated with high accuracy.

The air conditioner with natural circulation according to the present invention cools the room by sequentially connecting a compressor, an outdoor heat exchanger, an expansion valve, and an indoor heat exchanger with piping. The outlet of the evaporator and the inlet of the condenser are connected by a bypass pipe via a check valve, and the opening degree of the expansion valve is controlled so that the forced circulation operation by the compressor refrigeration cycle system and the cooling by the natural circulation refrigeration cycle system An air conditioner capable of switching between operation and operation, wherein an accumulator provided in parallel with the bypass pipe so as to store a difference between the amount of refrigerant required in the forced circulation operation and the natural circulation operation, and the forced circulation operation When the mode is switched to the natural circulation operation, a refrigerant recovery unit configured to recover the refrigerant stored in the accumulator is provided, and the natural circulation operation is performed after the refrigerant is recovered. Therefore, there is an effect that the respective abilities can be sufficiently exhibited as the optimum refrigerant amount in both the forced circulation operation and the natural circulation operation.

Further, the air conditioner with natural circulation according to the present invention comprises a compressor, and the refrigerant recovery control means comprises a high pressure pipe from the compressor outlet to the expansion valve inlet and a high pressure pipe from the expansion valve outlet to the compressor inlet. A second bypass pipe connecting the low pressure pipe and a high / low pressure bypass valve for controlling the amount of refrigerant flowing through the second bypass pipe are installed, and the opening of the expansion valve and the high / low pressure bypass valve are controlled. The air conditioner combined with natural circulation according to claim 3, characterized in that: A second bypass pipe between the compressor outlet and the accumulator inlet;
A high-low pressure bypass valve is provided, and the refrigerant recovery means is constituted by controlling the opening degree of the expansion valve and the high-low pressure bypass valve, so that the reliability of the compressor can be reduced without lowering the suction pressure of the compressor. There is an effect that the refrigerant can be recovered while securing the same.

Further, the air conditioner with natural circulation according to the present invention includes an indoor heat load detecting means, a refrigeration cycle capacity calculating means for calculating a cooling capacity in each of the refrigeration cycles,
According to the cooling capacity in the natural circulation refrigeration cycle system obtained by the refrigeration cycle capacity calculation means and the indoor heat load detected by the indoor heat load detection means, the forced circulation operation by the compressor refrigeration cycle system and the natural circulation refrigeration cycle Switching between natural circulation operation by the system and the refrigeration cycle switching means for performing the refrigerant recovery control, such as when the outside air temperature is high,
When the effect of the natural circulation operation is small, there is an effect that it is possible to prevent the power consumption due to the activation of the compressor and the shortening of the life due to the frequent opening and closing of the electronic expansion valve without performing the refrigerant recovery control.

Further, the air conditioner with combined use of natural circulation according to the present invention is characterized in that, in each of the refrigeration cycles of a compressor refrigeration cycle system or a natural circulation refrigeration cycle system, either of the compressor refrigeration cycle system or the natural circulation refrigeration cycle system is used. When an abnormality is detected from one of the refrigeration cycles, the refrigeration cycle is switched to another refrigeration cycle in which no abnormality is detected. Therefore, even if an abnormality occurs during operation of one of the refrigeration cycles, the cooling operation can be continued in the other refrigeration cycle. This has the effect.

Further, the air conditioner with natural circulation of the present invention is provided with a heat exchanger temperature detecting means for detecting the temperature of the evaporator or the condenser, and the heat exchanger temperature detecting means and the refrigeration cycle capacity calculating means. Since the operation state of each refrigeration cycle of the compressor refrigeration cycle system or the natural circulation refrigeration cycle system is detected, the normal / abnormal condition of each refrigeration cycle can be determined by a simple method.

[Brief description of the drawings]

FIG. 1 is a refrigerant circuit diagram illustrating an air conditioner with combined use of natural circulation according to Embodiment 1 of the present invention.

FIG. 2 is an installation configuration diagram showing a natural circulation combined type air conditioner according to Embodiment 1 of the present invention.

FIG. 3 is a control block diagram showing an air conditioner with natural circulation according to Embodiment 1 of the present invention;

FIG. 4 is a control flowchart showing the air conditioner with combined use of natural circulation according to the first embodiment of the present invention.

FIG. 5 is a control block diagram showing an air conditioner combined with natural circulation according to a second embodiment of the present invention.

FIG. 6 is a refrigerant circuit diagram showing an air conditioner with natural circulation according to Embodiment 3 of the present invention.

FIG. 7 is a control block diagram showing an air conditioner combined with natural circulation according to a third embodiment of the present invention.

FIG. 8 is a control flowchart showing an air conditioner combined with natural circulation according to Embodiment 3 of the present invention.

FIG. 9 is a control flowchart showing an air conditioner combined with natural circulation according to a fourth embodiment of the present invention.

FIG. 10 is a control block diagram showing an air conditioner combined with natural circulation according to a fifth embodiment of the present invention.

FIG. 11 is a control flowchart showing an air conditioner combined with natural circulation according to a fifth embodiment of the present invention.

FIG. 12 is a control block diagram showing a specific example of abnormality detection of an air conditioner with natural circulation according to Embodiment 5 of the present invention.

FIG. 13 is a configuration diagram of a refrigerant circuit showing a conventional natural circulation combined type air conditioner.

[Explanation of symbols]

1 outdoor unit, 2 indoor unit, 3 compressor, 4
Condenser, 5 expansion valve, 6 evaporator, 7 condenser fan, 8 evaporator fan, 9 bypass pipe, 10 check valve, 11 liquid pipe, 12 gas pipe, 13 open / close valve,
14 accumulator, 17 second bypass pipe, 18
High / low pressure bypass valve, 100b indoor heat load detecting means,
100c Refrigeration cycle capacity calculation means, 100d Refrigeration cycle switching means.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Ittaro Akiyama 2-6-2 Otemachi, Chiyoda-ku, Tokyo Inside Mitsubishi Electric Engineering Co., Ltd. (72) Inventor Akio Fukushima 2-2-2 Marunouchi, Chiyoda-ku, Tokyo No. 3 Mitsubishi Electric Corporation

Claims (7)

[Claims] 1. An air conditioner for cooling a room by sequentially connecting a compressor, an outdoor heat exchanger, an expansion valve, and an indoor heat exchanger by piping, and inverting the evaporator outlet and the condenser inlet. An air conditioner that is connected by a bypass pipe via a stop valve and controls the opening degree of the expansion valve to switch between forced circulation operation by a compressor refrigeration cycle system and cooling operation by a natural circulation refrigeration cycle system. An indoor heat load detecting means, a refrigeration cycle capacity calculating means for calculating a cooling capacity in the natural circulation operation, and a cooling capacity in the natural circulation operation obtained by the refrigeration cycle capacity calculating means and the indoor heat load detecting means. An air conditioner combined with natural circulation, characterized by comprising a refrigeration cycle switching means for switching between the forced circulation operation and the natural circulation operation according to the indoor heat load. 2. The natural circulation combined air according to claim 1, further comprising an indoor temperature detecting means and an outside air temperature detecting means, wherein the natural circulation refrigeration cycle capacity is obtained from the room temperature and the outside air temperature. Harmony machine. 3. An air conditioner for cooling a room by sequentially connecting a compressor, an outdoor heat exchanger, an expansion valve, and an indoor heat exchanger with piping, and inverting the evaporator outlet and the condenser inlet. An air conditioner that is connected by a bypass pipe via a stop valve and controls the opening degree of the expansion valve to switch between forced circulation operation by a compressor refrigeration cycle system and cooling operation by a natural circulation refrigeration cycle system. An accumulator provided in parallel with the bypass pipe so as to store a difference between the amount of refrigerant required in the forced circulation operation and the natural circulation operation, and when switching from the forced circulation operation to the natural circulation operation, An air conditioner combined with natural circulation, comprising a refrigerant recovery means for recovering the refrigerant stored in the accumulator, and performing the natural circulation operation after recovering the refrigerant. 4. A refrigerant recovery control means, comprising: a second bypass pipe connecting a high pressure pipe from the compressor outlet to the expansion valve inlet and a low pressure pipe from the expansion valve outlet to the compressor inlet; 4. A natural circulation combined type according to claim 3, wherein a high / low pressure bypass valve for controlling the amount of refrigerant flowing through the bypass pipe is provided, and the opening of the expansion valve and the high / low pressure bypass valve are controlled. Air conditioner. 5. An indoor heat load detecting means, a refrigeration cycle capacity calculating means for calculating a cooling capacity in each of the refrigeration cycles, a cooling capacity in the natural circulation refrigeration cycle system obtained by the refrigeration cycle capacity calculating means and the indoor heat. Refrigeration cycle switching for switching between forced circulation operation by the compressor refrigeration cycle system and natural circulation operation by the natural circulation refrigeration cycle system and performing the refrigerant recovery control in accordance with the indoor heat load detected by the load detection means. 5. The air conditioner combined with natural circulation according to claim 3, further comprising means. 6. In each refrigeration cycle of the compressor refrigeration cycle system or the natural circulation refrigeration cycle system, when an abnormality is detected from either the compressor refrigeration cycle system or the natural circulation refrigeration cycle system, the abnormality is detected. 6. The air conditioner with natural circulation according to claim 1, wherein the air conditioner is switched to another refrigeration cycle that is not detected. 7. A heat exchanger temperature detecting means for detecting a temperature of the evaporator or the condenser, wherein the heat exchanger temperature detecting means and the refrigeration cycle capacity calculating means determine the compressor refrigeration cycle system or 7. The air conditioner combined with natural circulation according to claim 1, wherein an operation state of each refrigeration cycle of the natural circulation refrigeration cycle system is detected.